/mcpFor this feature, Extension Mobility profile can be added to the control list in addition to the devices. When this profile is added to the control list and an Extension Mobility Cross Cluster user logs in to or logs out of a device within a cluster or either across the cluster, Cisco TSP notifies the application with required Phone Create/Line_Create and Phone_Remove/Line_Remove events. Interface Changes None Message Sequences See Extension Mobility Cross Cluster, on page 733. Backward Compatibility This feature is backward compatible. Extension Mobility Memory Optimization Option The Extension Mobility (EM) feature supports Cisco Unified TSP to use TAPI LINE_CREATE / LINE_REMOVE mechanism to dynamically create and remove line devices resulting from EM login or logout. TAPI, by design, does not remove a device dynamically and marks the device as ‘not available’. It remains in memory until the provider is shutdown. As a result, when the EM feature is used, memory utilization grows over time (during login/logout operations) until the memory is exhausted. In many cases, the only workaround is to restart the telephony service or reboot a TAPI client machine. The EM Memory Optimization Option feature is intended to minimize the usage of LINE_CREATE / LINE_REMOVE in EM-related scenarios by reusing TAPI device IDs for lines from different EM profiles loaded on the same IP Phone. Lines with the same index in different EM profiles share the same TAPI line device ID. The feature can be enabled or disabled by using the registry settings. By default, the feature is disabled so that the existing applications are not affected. If the feature is enabled, LINE_CREATE messages are used by Cisco Unified TSP only for the first time when an EM profile is loaded on a particular IP Phone. After the EM line is created, it is not removed with LINE_REMOVE. It is instead placed in the Inactive state when EM logout occurs. Operations cannot be performed when a device is in the Inactive state and the LINEERR_DEVICE_INACTIVE error returns if an operation is invoked. The line is reactivated when an EM profile is reloaded on the IP Phone as a result of a new EM login. Along with the line reactivation notification, the application is also notified that line device capabilities have changed. The Other-Device State Notification feature is utilized for delivering active, inactive, and capability change messages to an application. For more information, see Other-Device State Notification, on page 79. The EM Memory Optimization Option feature intends to minimize the usage of LINE_CREATE/LINE_REMOVE messages. Even if the feature is enabled, an application can still receive the LINE_CREATE and LINE_REMOVE messages in some scenarios. So the application has to be written in a way that it can handle the existing LINE_CREATE/LINE_REMOVE events along with the new LineActive/LineInactive notifications. Note Cisco Unified TAPI Developers Guide for Cisco Unified Communications Manager, Release 15 and SUs 64 Features Supported by TSP Extension Mobility Memory Optimization Option